a. Field of the Invention
This invention relates to a method of making a container having a separable inner lining and outer shell, and in particular to methods of forming a flexible lining for a container and methods of lining a container with a pre-formed lining. This invention also relates to apparatus for use in such methods.
b. Related Art
There is a general desire and need to reduce the amount of waste that is produced and a drive to recycle as much as possible. One particular area that is receiving much attention is packaging.
One sector of interest is disposable or paper cups. These are often made from pre-laminated card which is then rolled and formed to create a disposable cup. The use of laminated card can have the benefits of being more resource and energy efficient than using plastic alone, however, combining materials in this way prevents the cups being recycled with unlaminated cardboard or pure plastic, and therefore, most disposable cups end up in landfill.
Typically the laminated card comprises a paper-based substrate layer and a polymeric coating, which in the case of disposable cup is usually polyethylene. The coating is waterproof and acts as a liquid barrier between the contents of the cup and the paper-based substrate. Generally, the laminated card has a polymeric or plastics coating on only one side of the substrate when used to form cups to hold hot beverages, whereas the laminated card will often have a plastics coating on both sides of the paper-based substrate when used to form cups to hold cold beverages.
However, these coatings prevent the material from fully decomposing. In particular, during the recycling process typically used for paper products, the plastics coating prevents or inhibits water breaking up the paper fibres of the substrate during the process of pulping. Additionally, the plastics coating is difficult to separate and therefore contaminates the paper pulp that is formed.
Of note is the fact that an estimated 58 billion paper cups end up in landfill every year in the USA, and this equates to several million trees being felled annually, as most of the paper-based material used to form the cups is virgin, non-recycled material.
There is, therefore, a need to find a more environmentally friendly alternative. However, commercial considerations mean that it is desirable for any alternative to be able to be manufactured at similar speeds and in similar volumes to existing paper cups and also with the same degree of reliability and consistency. Current paper cup making machines typically output at a rate of up to 100-200 cups per minute with a failure/leakage rate of about one cup in every million.
Containers substantially similar to disposable cups are also increasingly used to contain other foodstuffs, such as yogurt and ice-cream. In these applications it is necessary for the container to be able to store the contents of the container for a desired length of time, and also be able to withstand a consumer removing the contents of the container with a suitable implement such as a spoon. It is necessary, therefore, for the container to be able to withstand scraping along its base and side wall without a reduction in integrity.
It is an object of the present invention to provide a method of manufacturing a container that overcomes the above-mentioned problems.